That, is an Adapter, not a cheater, Cheater implies something else in the RV world.
But to answer your question: IF the only thing you have on is the converter,, Then when using one of those adapter plugs you will get one of three things.
No small extension cord: You get either normal battery charging or, if the converter is big enough you might get "The click of darkness" (Trip a 15 amp breaker) I have a Progressive Dynamics 9280, with wizard, that is a fairly large converter, it's on a 15 amp breaker no problems.
But be careful of additional loads.
If you have a long small (say 14 ga) 15 amp cord,, You may see reduced voltage at the RV and that could affect converter operation
So your options are
Normal operation
Tripped breaker
Reduced due to voltage drop in the small extension cord.
HOWEVER, if the cord is that long, please upgrade it. My long cord is 12ga and it does NOT affect charging at all. (100')